Liquid crystal compounds exhibiting negative anisotropy of permittivity

Abstract

Novel liquid crystal compound having a negative and absolutely large value of dielectric anisotropy, being excellent in compatibility with other liquid crystalline compounds at a low temperature and being stable chemically and physically, as well as a liquid crystal composition comprising this compound, and a liquid crystal display device comprising this liquid crystal composition are provided, said compound is expressed by the general formula (1):wherein A1, A2, A3 and A4 represent a single bond, 1,4-cyclohexylene, 1,4-phenylene which may be substituted with a fluorine atom(s) or the like; B1, B2, B3 and B4 represent a single bond, 1,2-ethylene, 1,2-ethenylene, 1,2-ethynylene, oxymethylene, methyleneoxy or the like; R1 and R2 represent an alkyl group having 1 to 10 carbon atoms or the like; and Z represents (I) to (VI):wherein X represents H or F, and Y represents difluoromethyl group, difluoromethoxy group, formyl group or carboxyl group.

What is claimed is:  
     
       1. A liquid crystalline compound expressed by the general formula (1): 
       
         
           R 1 —A 1 —B 1 —A 2 —B 2 —A 3 —B 3 —Z—B 4 —A 4 —R 2   (1)  
         
       
       wherein A 1 , A 2 , A 3  and A 4  each independently represent a single bond, 1,4-cyclohexylene, 1,4-phenylene which may be substituted with a fluorine atom(s), dioxane-2,5-diyl, pyrimidine-2,5-diyl, piperidine-1,4-diyl, pyridine-2,5-diyl which may be substituted with a fluorine atom(s) or 1-sila-1,4-cyclohexyllene; Z represents a group selected from divalent groups expressed by partial structural formulas (I) to (VI):                    
       wherein X represents a hydrogen atom or a fluorine atom, and Y represents a difluoromethyl group, a difluoromethoxy group, a formyl group or a carboxyl group; B 1 , B 2 , B 3  and B 4  each independently represent a single bond, 1,2-ethylene, 1,2-ethenylene, -1,2-ethynylene, oxymethylene, methyleneoxy, carbonyloxy, oxycarbonyl or 1,4-butylene group, provided that when Z is a group represented by the partial structural formula (III), then B 4  is neither oxymethylene nor oxycarbonyl group, and that when Z is a group represented by the partial structural formula (IV), then B 3  is neither methyleneoxy nor carbonyloxy group, and that when Z is a group represented by the partial structural formula (I), (II), (III) or (IV), then A 1 , A 2 , A 3  and A 4  do not simultaneously represent a single bond, and that when Z is a group represented by the partial structural formula (V) or (VI), then Y does not represent a carboxyl group; R 1  and R 2  each independently represent an alkyl group or a fluoroalkyl group substituted with at least one fluorine atom having 1 to 10 carbon atoms in which alkyl group or fluoroalkyl group one or not adjacent two or more methylene groups may be replaced by an oxygen atom, a sulfur atom or —CH═CH—. 
     
     
       2. The liquid crystalline compound as described in  claim 1  wherein Z is a group represented by the partial structural formula (I). 
     
     
       3. The liquid crystalline compound as described in  claim 1  wherein Z is a group represented by the partial structural formula (II). 
     
     
       4. The liquid crystalline compound as described in  claim 1  wherein Z is a group represented by the partial structural formula (V). 
     
     
       5. The liquid crystalline compound as described in  claim 1  wherein Z is a group represented by the partial structural formula (VI). 
     
     
       6. A liquid crystal composition comprising two or more components at least one of which is a liquid crystalline compound described in any one of  claims 1  to  5 . 
     
     
       7. A liquid crystal composition comprising, as a first component, at least one liquid crystalline compound described in any one of  claims 1  to  5  above, and as a second component, at least one compound selected from the group consisting of the compounds expressed by any one of the formulas (2), (3) and (4):                    
       wherein R 3  represents an alkyl group having 1 to 10 carbon atoms in which alkyl group one or not adjacent two or more methylene groups may be replaced by an oxygen atom or —CH═CH—, and any hydrogen atom thereof may be replaced by a fluorine atom; Y 1  represents a fluorine atom, a chlorine atom, OCF 3 , OCF 2 H, CF 3 , CF 2 H, CFH 2 , OCF 2 CF 2 H or OCF 2 CFHCF 3 ; L 1  and L 2  each independently represent a hydrogen atom or a fluorine atom; Z 1  and Z 2  each independently represent a 1,2-ethylene group, a 1,4-butylene group, —COO—, —CF 2 O—, —OCF 2 —, —CH═CH— or a single bond; ring B represents trans-1,4-cyclohexylene, 1,3-dioxane-2,5-diyl or 1,4-phenylene in which any hydrogen atom on the ring may be replaced by a fluorine atom; and ring C represents trans-1,4-cyclohexylene, or 1,4-phenylene in which any hydrogen atom on the ring may be replaced by a fluorine atom. 
     
     
       8. A liquid crystal composition comprising, as a first component, at least one liquid crystalline compound described in any one of  claims 1  to  5  above, and, as a second component, at least one compound selected from the group consisting of compounds expressed by the formulas (5) and (6):                    
       wherein R 4  and R 5  each independently represent an alkyl group having 1 to 10 carbon atoms in which alkyl group one or not adjacent two or more methylene groups may be replaced by an oxygen atom or —CH═CH—, and any hydrogen atom thereof may be replaced by a fluorine atom; Y 2  represents a —CN group or —C≡C—CN; ring E represents trans-1,4-cyclohexylene, 1,4-phenylene, 1,3-dioxane-2,5-diyl or pyrimidine-2,5-diyl; ring G represents trans-1,4-cyclohexylene, 1,4-phenylene 4-phenylene in which any hydrogen atom on the ring may be replaced by a fluorine atom or pyrimidine-2,5-diyl; ring H represents trans-1,4-cyclohexylene or 1,4-phenylene; Z 3  represents a 1,2-ethylene group, —COO— or a single bond; L 3 , L 4 and L 5 each independently represent a hydrogen atom or a fluorine atom; and b, c and d each independently represent 0 or 1. 
     
     
       9. A liquid crystal composition comprising, as a first component, at least one liquid crystalline compound described in any one of  claims 1  to  5  above, and as a second component, at least one compound selected from the group consisting of the compounds expressed by any one of the formulas (7), (8) and (9):                    
       wherein R 6  and R 7  each independently represent an alkyl group having 1 to 10 carbon atoms in which alkyl group one or not adjacent two or more methylene groups may be replaced by an oxygen atom or —CH═CH—, and any hydrogen atom thereof may be replaced by a fluorine atom; rings I, J and K each independently represent trans-1,4-cyclohexylene, pyrimidine-2,5-diyl or 1,4-phenylene in which any hydrogen atom on the ring may be replaced by a fluorine atom; and Z 4  and Z 5  each independently represent —C≡C—, —COO—, —CH 2 CH 2 —, —CH═CH— or a single bond. 
     
     
       10. A liquid crystal composition comprising, as a first component, at least one liquid crystalline compound described in any one of  claims 1  to  5  above, as a second component, at least one compound selected from the group consisting of the compounds expressed by any one of the formulas (2), (3) and (4), and, as a third component, at least one compound selected from the group consisting of the compounds expressed by any one of the formulas (7), (8) and (9):                    
       wherein R 3  represents an alkyl group having 1 to 10 carbon atoms in which alkyl group one or not adjacent two or more methylene groups may be replaced by an oxygen atom or —CH═CH—, and any hydrogen atom thereof may be replaced by a fluorine atom; Y 1  represents a fluorine atom, a chlorine atom, OCF 3 , OCF 2 H, CF 3 , CF 2 H, CFH 2 , OCF 2 CF 2 H or OCF 2 CFHCF 3 ; L 1  and L 2  each independently represent a hydrogen atom or a fluorine atom; Z 1  and Z 2  each independently represent a 1,2-ethylene group, a 1,4-butylene group, —COO—, —CF 2 O—, —OCF 2 —, —CH═CH—or a single bond; ring B represents trans-1,4-cyclohexylene, 1,3-dioxane-2,5-diyl or 1,4-phenylene in which any hydrogen atom on the ring may be replaced by a fluorine atom; and ring C represents trans-1,4-cyclohexylene, or 1,4-phenylene in which any hydrogen atom on the ring on the ring may be replaced by a fluorine atom,                    
       wherein R 6  and R 7  each independently represent an alkyl group having 1 to 10 carbon atoms in which alkyl group one or not adjacent two or more methylene groups may be replaced by an oxygen atom or —CH═CH—, and any hydrogen atom thereof may be replaced by a fluorine atom; rings I, J and K each independently represent trans-1,4-cyclohexylene, pyrimidine-2,5-diyl or 1,4-phenylene in which any hydrogen atom on the ring may be replaced by a fluorine atom; and Z 4  and Z 5  each independently represent —C≡C—, —COO—, —CH 2 CH 2 —, —CH═CH— or a single bond. 
     
     
       11. A liquid crystal composition comprising, as a first component, at least one liquid crystalline compound described in any one of  claims 1  to  5  above, as a second component, at least one compound selected from the group consisting of the compounds expressed by any one of the formulas (10), (11) and (12):                    
       wherein R 8  and R 9  each independently represent an alkyl group having 1 to 10 carbon atoms in which alkyl group one or not adjacent two or more methylene groups may be replaced by an oxygen atom or —CH=CH—, and any hydrogen atom thereof may be replaced by a g fluorine atom; rings L and M each independently represent trans-1,4-cyclohexylene or 1,4-phenylene; L 6  and L 7  each independently represent a hydrogen atom or a fluorine atom but never be hydrogen atoms at the same time; and Z 6  and Z 7  each independently represent —CH 2 CH 2 —, —CH 2 O— or a single bond. 
     
     
       12. A liquid crystal composition comprising, as a first component, at least one liquid crystalline compound described in any one of  claims 1  to  5  above, as a second component, at least one compound selected from the group consisting of the compounds expressed by any one of the formulas (7), (8) and (9), and, as a third component, at least one compound selected from the group consisting of the compounds expressed by any one of the formulas (10), (11) and (12):                    
       wherein R 6  and R 7  each independently represent an alkyl group having 1 to 10 carbon atoms in which alkyl group one or not adjacent two or more methylene groups may be replaced by an oxygen atom or —CH═CH—, and any hydrogen atom thereof may be replaced by a fluorine atom; rings I, J and K each independently represent trans-1,4-cyclohexylene, pyrimidine-2,5-diyl or 1,4-phenylene in which any hydrogen atom on the ring may be replaced by a fluorine atom; and Z 4  and Z 5  each independently represent —C≡C—, —COO—, —CH 2 CH 2 —, —CH═CH— or a single bond,                    
       wherein R 8  and R 9  each independently represent an alkyl group having 1 to 10 carbon atoms in which alkyl group one or not adjacent two or more methylene groups may be replaced by an oxygen atom or —CH=CH—, and any hydrogen atom thereof may be replaced by a fluorine atom; rings L and M each independently represent trans-1,4-cyclohexylene or 1,4-phenylene; L 6  and L 7  each independently represent a hydrogen atom or a fluorine atom but never be hydrogen atoms at the same time; and Z 6  and Z 7  each independently represent —CH 2 CH 2 —, —CH 2 O—or a single bond. 
     
     
       13. A liquid crystal composition comprising, as a first component, at least one liquid crystalline compound described in any one of  claims 1  to  5  above, as a second component, at least one compound selected from the group consisting of compounds expressed by the formulas (5) and (6), and, as a third component, at least one compound selected from the group consisting of the compounds expressed by any one of the formulas (7), (8) and (9):                    
       wherein R 4  and R 5  each independently represent an alkyl group having 1 to 10 carbon atoms in which alkyl group one or not adjacent two or more methylene groups may be replaced by an oxygen atom or —CH═CH—, and any hydrogen atom thereof may be replaced by a fluorine atom; Y 2  represents a —CN group or —C≡C—CN; ring E represents trans-1,4-cyclohexylene, 1,4-phenylene, 1,3-dioxane-2,5-diyl or pyrimidine-2,5-diyl; ring G represents trans-1,4-cyclohexylene, 1,4-phenylene 4-phenylene in which any hydrogen atom on the ring may be replaced by a fluorine atom or pyrimidine-2,5-diyl; ring H represents trans-1,4-cyclohexylene or 1,4-phenylene; Z 3  represents a 1,2-ethylene group, —COO— or a single bond; L 3 , L 4  and L 5  each independently represent a hydrogen atom or a fluorine atom; and b, c and d each independently represent 0 or 1,                    
       wherein R 6  and R 7  each independently represent an alkyl group having 1 to 10 carbon atoms in which alkyl group one or not adjacent two or more methylene groups may be replaced by an oxygen atom or —CH═CH—, and any hydrogen atom thereof may be replaced by a fluorine atom; rings I, J and K each independently represent trans-1,4-cyclohexylene, pyrimidine-2,5-diyl or 1,4-phenylene in which any hydrogen atom on the ring may be replaced by a fluorine atom; and Z 4  and Z 5  each independently represent —C≡C—, —COO—, —CH 2 CH 2 —, —CH═CH— or a single bond. 
     
     
       14. A liquid crystal composition comprising, as a first component, at least one liquid crystalline compound described in any one of  claims 1  to  5  above, as a second component, at least one compound selected from the group consisting of the compounds expressed by any one of the formulas (2), (3) and (4), as a third component, at least one compound selected from the group consisting of compounds expressed by the formulas (5) and (6), and, as a fourth component, at least one compound selected from the group consisting of the compounds expressed by any one of the formulas (7), (8) and (9):                    
       wherein R 3  represents an alkyl group having 1 to 10 carbon atoms in which alkyl group one or not adjacent two or more methylene groups may be replaced by an oxygen atom or —CH═CH—, and any hydrogen atom thereof may be replaced by a fluorine atom; Y 1  represents a fluorine atom a chlorine atom, OCF 3 , OCF 2 H, CF 3 , CF 2 H, CFH 2 , OCF 2 CF 2 H or OCF 2 CFHCF 3 ; L 1  and L 2  each independently represent a hydrogen atom or a fluorine atom; Z 1  and Z 2  each independently represent a 1,2-ethylene group, a 1,4-butylene group, —COO—, —CF 2 O—, —OCF 2 —, —CH=CH—or a single bond; ring B represents trans-1,4-cyclohexylene, 1,3-dioxane-2,5-diyl or 1,4-phenylene in which any hydrogen atom on the ring may be replaced by a fluorine atom; and ring C represents trans-1,4-cyclohexylene, or 1,4-phenylene in which any hydrogen atom on the ring may be replaced by a fluorine atom,                    
       wherein R 4  and R 5  each independently represent an alkyl group having 1 to 10 carbon atoms in which alkyl group one or not adjacent two or more methylene groups may be replaced by an oxygen atom or —CH═CH—, and any hydrogen atom thereof may be replaced by a fluorine atom; Y 2  represents a —CN group or —C≡C—CN; ring E represents trans-1,4-cyclohexylene, 1,4-phenylene, 1,3-dioxane-2,5-diyl or pyrimidine-2,5-diyl; ring G represents trans-1,4-cyclohexylene, 1,4-phenylene 4-phenylene in which any hydgrogen atom on the ring may be replaced by a fluorine atom or pyrimidine-2,5-diyl; ring H represents trans-1,4-cyclohexylene or 1,4-phenylene; Z 3  represents a 1,2-ethylene group, —COO— or a single bond; L 3  and L 4  and L 5  each independently represent a hydrogen atom or a fluorine atom; and b, c and d each independently represents 0 or 1,                    
       wherein R 6  and R 7  each independently represent an alkyl group having 1 to 10 carbon atoms in which alkyl group one or not adjacent two or more methylene groups may be replaced by an oxygen atom or —CH═CH—, and any hydrogen atom thereof may be replaced by a fluorine atom; rings I, J and K each independently represent trans-1,4-cyclohexylene, pyrimidine-2,5-diyl or 1,4-phenylene in which any hydrogen atom on the ring may be replaced by a fluorine atom; and Z 4  and Z 5  each independently represent —C≡C—, —COO—, —CH 2 CH 2 —, —CH═CH—or a single bond. 
     
     
       15. A liquid crystal composition recited in  claim 6  wherein the liquid crystal composition further comprises an optically active compound. 
     
     
       16. A liquid crystal display device comprising the liquid crystal composition as recited in  claim 6 .